Rolling locking assembly for camshaft phaser

ABSTRACT

A camshaft phaser is provided that includes a stator and a rotor having a locking assembly. The locking assembly has a first unlocked position and a second locked position and is configured to roll against the stator in the first unlocked position and lock the rotor to the stator in the second locked position. The locking assembly can include a locking pin, a retention insert, and a rolling element arranged within the retention insert.

TECHNICAL FIELD

Example aspects described herein relate to camshaft phasers, and, more particularly, to camshaft phasers utilized within an internal combustion (IC) engine.

BACKGROUND

Camshaft phasers are utilized within IC engines to adjust timing of an engine valve event to modify performance, efficiency and emissions. Hydraulically actuated camshaft phasers can be configured with a rotor and stator arrangement. The rotor can be connected to a camshaft and actuated hydraulically in clockwise or counterclockwise directions relative to the stator to achieve variable engine valve timing. The rotor can include a locking pin assembly that selectively locks the rotor to the stator.

SUMMARY

In an example embodiment, a camshaft phaser includes a stator and a rotor, the rotor having a plurality of vanes that form fluid chambers with the stator. The stator can include an endless drive band interface that is arranged to non-rotatably connect the stator to a power source of an internal combustion engine. The rotor includes a locking assembly that has a first unlocked position and a second locked position. The locking assembly is configured to: (i) roll against the stator in the first unlocked position, and (ii) lock the rotor to the stator in the second locked position. In an example embodiment, the locking assembly rolls against a front cover that is non-rotatably attached to the stator.

The locking assembly can include a locking pin, a retention insert, and a rolling element arranged within the retention insert, the rolling element configured to roll against the stator in the first unlocked position. The locking assembly is configured to selectively lock the rotor to the stator. The rolling element can be a ball or a roller. The locking assembly can also include a force generator or bias spring arranged between the locking pin and the retention insert. At least a portion of the locking assembly, including, by not limited to the locking pin and retention insert, can be received by a locking pin aperture that is arranged within the rotor. In an example embodiment, the locking pin aperture is arranged within one of the plurality of vanes of the rotor. The locking pin can protrude from a locking end of the locking pin aperture to engage the stator (or rear cover) in the second locked position. A vent passage can be configured in an axial face of the rotor and is fluidly connected to the locking pin aperture. In an example embodiment, the vent passage is transverse to a central axis of the locking pin aperture.

The retention insert can include at least one outlet that is configured to provide an exit pathway for hydraulic fluid and/or air from the locking pin aperture. The at least one outlet can be fluidly connected to the vent passage.

A method for operating a camshaft phaser is provided that includes:

-   -   providing a camshaft phaser that includes a stator, a rotor         having a plurality of vanes that form fluid chambers with the         stator, and a pressureless-locked locking assembly that         selectively locks the rotor to the stator or selectively unlocks         the rotor from the stator;     -   actuating the locking assembly to unlock the rotor from the         stator, defining a first unlocked position; in the first         unlocked position, the rotor is allowed to rotate relative to         the stator; and     -   rotating the rotor relative to the stator, causing the locking         assembly to roll against the stator.

The rotor can include a locking pin aperture that receives at least a portion of the locking pin assembly. The locking assembly can be moved to the first unlocked position by hydraulic fluid pressure, and the rotor can be rotated relative to the stator by hydraulic fluid pressure.

A further step of operating the camshaft phaser can include actuating the locking assembly to a second locked position which prevents rotation of the rotor relative to the stator. The locking assembly can be actuated to the second locked position by a bias spring that is arranged within the locking assembly. The bias spring can provide a force that is greater than a hydraulic fluid force acting on the locking assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other features and advantages of the embodiments described herein, and the manner of attaining them, will become apparent and better understood by reference to the following descriptions of multiple example embodiments in conjunction with the accompanying drawings. A brief description of the drawings now follows.

FIG. 1 is an exploded perspective view of an example embodiment of a camshaft phaser that includes a rotor that is hydraulically actuated relative to a stator, and a locking assembly that selectively locks the rotor to the stator.

FIG. 2 is a perspective view of the camshaft phaser of FIG. 1 together with a hydraulic fluid control valve.

FIG. 3 is an exploded perspective view of an assembly of the rotor and stator together with a portion of the locking assembly of FIG. 1.

FIG. 4 is a partial perspective view of the camshaft phaser of FIG. 1 with a section removed to illustrate a hydraulic fluid actuation path for the locking assembly.

FIG. 5 is a partial perspective view of the camshaft phaser of FIG. 1 with a section removed to illustrate a vent path for the locking assembly.

FIGS. 6A and 6B are partial cross-sectional views taken from FIG. 2 that show the locking assembly in respective first unlocked and second locked positions.

FIG. 7A is a perspective view of a portion of the locking assembly of FIG. 1 that includes a retention insert and rolling element.

FIG. 7B is a perspective view of an embodiment of a retention insert and rolling element.

FIG. 8 is a schematic view of the camshaft phaser together with a camshaft, with the camshaft phaser non-rotatably connected to a crankshaft via an endless drive band.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Identically labeled elements appearing in different figures refer to the same elements but may not be referenced in the description for all figures. The exemplification set out herein illustrates at least one embodiment, in at least one form, and such exemplification is not to be construed as limiting the scope of the claims in any manner. Certain terminology is used in the following description for convenience only and is not limiting. The words “inner,” “outer,” “inwardly,” and “outwardly” refer to directions towards and away from the parts referenced in the drawings. Axially refers to directions along a diametric central axis. Radially refers to directions that are perpendicular to the central axis. The words “left”, “right”, “up”, “upward”, “down”, and “downward” designate directions in the drawings to which reference is made. The terminology includes the words specifically noted above, derivatives thereof, and words of similar import.

Referring to FIG. 1, an exploded perspective view of an example embodiment of a camshaft phaser 10 is shown that includes a front cover 50, a stator 40, a rotor 20, a rear cover 60, a bias spring 66, and a timing wheel 68. A locking assembly 70 that can selectively lock and unlock the rotor 20 from the rear cover 60, is also shown within FIG. 1. FIG. 2 shows the camshaft phaser 10 of FIG. 1 together with a hydraulic fluid control valve 80. FIG. 3 shows an exploded perspective view of the rotor 20, stator 40, and a portion of the locking assembly 70 of FIG. 1. FIG. 4 shows a partial perspective view of the camshaft phaser 10 with a section removed to show a hydraulic fluid actuation path for the locking assembly 70. FIG. 5 shows a partial perspective view of the camshaft phaser 10 with a section removed to show a vent path of the locking assembly 70. FIGS. 6A and 6B show partial cross-sectional views taken from FIG. 2 of the locking assembly 70 in respective first unlocked and second locked positions. FIGS. 7A and 7B show two different example embodiments of a retention insert 78, 78A and a rolling element 94, 94A. FIG. 8 shows a schematic view of the camshaft phaser 10 together with a camshaft 14, with the camshaft phaser 10 non-rotatably connected to a crankshaft 16 via an endless drive band 18. The following discussion should be read in light of FIGS. 1 through 8.

The term “non-rotatably connected” can be used to help describe various connections of a camshaft phaser and respective adjacent components and is meant to signify two elements that are directly or indirectly connected in a way that whenever one of the elements rotate, both of the elements rotate in unison, such that relative rotation between these elements is not possible. Radial and/or axial movement of non-rotatably connected elements with respect to each other is possible, but not required.

The stator 40 of the camshaft phaser 10 is configured with an endless drive band interface 44 to rotationally connect the camshaft phaser 10 to any power source, such as the crankshaft 16 of an internal combustion (IC) engine. The endless drive band 18 can be a belt or a chain to facilitate a non-rotatable connection between the camshaft phaser 10 and the crankshaft 16, causing the camshaft phaser 10 to rotate around a rotational axis 12.

The rotor 20 of the camshaft phaser 10 is non-rotatably connected to the camshaft 14, achieved by an axial clamping of the rotor 20 to the camshaft 14 via the hydraulic fluid control valve 80. The hydraulic fluid control valve 80 is configured with external threads 82 that engage internal threads (not shown) of the camshaft 14 to facilitate the axial clamping. Other ways to attach the rotor 20 to the camshaft 14 are also possible. To ensure proper orientation or timing of the camshaft phaser 10 relative to the camshaft 14, a timing protrusion 28 is arranged on the rotor 20.

The rotor 20 includes vanes 22 that extend radially outward from a hub 33 of the rotor 20. The stator 40 includes protrusions 42 that extend radially inward from an outer ring portion 46 of the stator 40. A plurality of fasteners 52 extend through front apertures 58 of the front cover 50, through clearance apertures 48 of the stator 40, and attach to locking apertures 64 of the rear cover 60. The front cover 50 and rear cover 60, together with the vanes 22 of the rotor 20 and protrusions 42 of the stator 40, form hydraulic actuation chambers 38 that are circumferentially arranged within the camshaft phaser 10. The camshaft phaser 10 is hydraulically actuated by pressurized hydraulic fluid F that is managed by the hydraulic fluid control valve 80 to move the rotor 20 either clockwise CW or counterclockwise CCW relative to the stator 40 by means of first hydraulic fluid ports 54 and second hydraulic fluid ports 56. The first and second hydraulic fluid ports 54, 56 are radially arranged in the hub 33 of the rotor 20, and serve to fluidly connect the hydraulic fluid control valve 80 with the hydraulic actuation chambers 38. As the rotor 20 is connected to the camshaft 14, clockwise CW and counterclockwise CCW relative movements of the rotor 20 relative to the stator 40 can advance or retard an engine valve event with respect to a four-stroke cycle of an IC engine. With reference to FIG. 3, clockwise CW rotation of the rotor 20 relative to the stator 40 can be achieved by: 1). pressurization of first chambers 55 via the first hydraulic fluid ports 54; and, 2). de-pressurization of second chambers 57 via the second hydraulic fluid ports 56. Likewise, counterclockwise CCW rotation of the rotor 20 relative to the stator 40 can be achieved by: 1). pressurization of the second chambers 57 via the second hydraulic fluid ports 56; and, 2). de-pressurization of the first chambers 55 via the first hydraulic fluid ports 54. First and second fluid ports 84, 86 of the hydraulic fluid control valve 80 are fluidly connected to the first and second hydraulic fluid ports 54, 56 to accomplish the previously described pressurization and de-pressurization actions. The hydraulic fluid control valve 80 can communicate electronically with an electronic controller 88 to control the camshaft phaser 10.

The locking assembly 70 includes a locking pin 74, a force generator 76, a retention insert 78, a rolling element 94, and a bushing 72. The rolling element 94 is arranged within the retention insert 78. The force generator 76 can be any component that provides a force on the locking pin 74 while permitting longitudinal movement of the locking pin 74. The force generator 76 can be a bias spring, elastomer or any component that meets the described functional attributes. In an example embodiment, the locking assembly 70 can either lock or unlock the rotor 20 from the stator 40, via the rear cover 60. The bushing 72 is received by a locking aperture 62 arranged within the rear cover 60. The bushing 72 can be hardened to suffice as a locking pin interface and can provide a low-cost alternative to hardening the rear cover 60. It could also be possible to eliminate the bushing 72 so that the locking pin interfaces directly with the locking aperture 62. The retention insert 78 is disposed within a locking pin aperture 23 of the rotor 20 and can provide: 1). an interface for the force generator 76; 2). an outlet 79 (at least one) for air and/or hydraulic fluid to exit a middle chamber 77 due to longitudinal movement of the locking pin 74 within the locking pin aperture 23; the outlet 79, as shown in FIGS. 5 and 6B, can be formed as one or more flats arranged on an outer circumference of the retention insert 78, however, other forms are possible; and, 3). a longitudinal stop for the locking pin 74 as it is displaced to unlock the rotor 20 from the stator 40, or, alternatively stated, to unlock the rotor 20 from the rear cover 60 which is non-rotatably attached to the stator 40.

With view to FIGS. 5 through 6B, a vent passage 25 is arranged on the rotor 20 at a non-locking end 24 of the locking pin aperture 23 to facilitate an exiting pathway for the air and/or hydraulic fluid that flows from the middle chamber 77 and through the outlet 79 of the retention insert 78. The vent passage 25 can be arranged transverse to a center axis 21 of the locking pin aperture 23, and includes a bottom surface 27, and sidewalls 26 that extend from an axial surface 35 of the rotor 20. Other forms of the vent passage 25 are possible compared to what is shown in the Figures.

The retention insert 78 can be fabricated from many materials, including, but not limited to plastic. The plastic can be filled with glass fibers to increase the structural integrity of the retention insert 78. The plastic retention insert 78 can be held in place within the locking pin aperture 23 by either a slip-fit or a press-fit. A press-fit can be incorporated to facilitate retention of the locking assembly 70 during initial assembly of the camshaft phaser 10. However, due to thermal expansion and inherent creep and stress relaxation of plastic that occurs, the press-fit can change to a slip-fit, rendering the retention insert 78 movable within the locking pin aperture 23 during normal operation of the camshaft phaser 10. When the locking pin 74 is displaced within the locking pin aperture 23 by pressurized hydraulic fluid F, displacement of the retention insert 78 within the locking pin aperture 23 can occur. This displacement can be limited or restricted by an inner axial surface 51 of the front cover 50, which serves as an abutment surface for the rolling element 94. A first end 90 of the retention insert 78 is configured with a reception pocket 91 to receive the rolling element 94, formed as a ball that interfaces with or rolls against the inner axial surface 51 of the front cover 50. The reception pocket 91 includes a retention lip 95 that retains the ball 94 within the reception pocket 91. In an example embodiment, a first diameter D1 of the ball 94 is larger than a second diameter D2 of the retention lip 95 which facilitates an assembly process in which the ball is ‘snapped’ into the reception pocket 91 and then held in place by the retention lip 95. FIG. 6B shows a fitment of the ball 94 within the reception pocket 91 relative to the retention lip 95. Upon rotation of the rotor 20 relative the stator 40, the rolling element 94 rotates or spins within the reception pocket 91 while rolling against the inner axial surface 51. This rolling interface prevents wear that occurs between the retention insert 78 and the inner axial surface 51. During actuation of the locking pin 74 by the hydraulic fluid F, a hydraulic fluid force F1 (a product of the pressure P1 of the hydraulic fluid F multiplied by the area μl of the locking pin on which the hydraulic fluid acts) overcomes a force F2 of the force generator 76 to move the locking pin 74 away from the rear cover 60 until an abutment surface 73 on a non-locking end 75 of the locking pin 74 stops against a stop surface 81 of the retention insert 78; stated otherwise, the locking pin 74, when applied with a hydraulic fluid force F1 that overcomes a force F2 of the force generator 76, moves away from the stator 40 to disengage with the stator 40. Without the rolling interface between the retention insert 78 and the front cover 50, wear can occur at this interface. The wear can be further increased with the presence of glass fibers within the plastic material of the retention insert 78.

For this disclosure, any component that is non-rotabably attached to the stator 40 can be classified as “the stator”. For example, since the front cover 50 is non-rotatably attached to the stator 40, it could be stated that the rolling element 94 rolls against the stator 40.

FIG. 7B shows an embodiment of a retention insert 78A that is configured to receive a rolling element 94A in a form of a roller that is received by a rectangular-shaped reception pocket 91A. The roller 94A can be a needle roller or a cylindrical roller, as defined in the art of rolling element bearings. Upon rotation of the rotor 20 relative to the stator 40, the roller 94A spins or rotates freely within the reception pocket 91A while rolling against the inner axial surface 51 of the front cover 50. In one embodiment, the roller 94A could be configured with retention recesses 97 at each of its ends that receive retention protrusions 98 arranged in the reception pocket 91B that retain the roller 94A at its rotational axis 96, such that rotation of the rotor 20 causes the roller 94A to spin or rotate about its rotational axis 96. While FIGS. 7A and 7B show two forms of rolling elements 94, 94A, several other forms are possible.

The locking assembly 70 selectively locks the rotor 20 to the stator 40 via the rear cover 60. FIG. 6A shows a first unlocked position of the locking pin 74, and FIG. 6B shows a second locked position of the locking pin 74. The locking assembly 70 is arranged in a “pressureless-locked” configuration, meaning that the rotor 20 will be locked to the stator 40 at hydraulic fluid pressures below a pressure threshold provided by the locking pin 74 and force generator 76 tandem. If detachment of the rotor 20 from the stator 40 is necessary, the electronically controlled hydraulic fluid control valve 80 can be actuated to provide hydraulic fluid from a pressurized hydraulic fluid source 87 to the locking assembly 70. FIG. 4 shows a hydraulic fluid pathway for actuation of the locking assembly 70. As shown, the locking pin 74 of the locking assembly 70 receives hydraulic fluid via a chamfer 30 arranged at a locking end 29 of the locking pin aperture 23 which is fluidly connected to a groove 32 arranged within an axial surface 31 of the rotor 20. The groove 32 is fluidly connected to one of the first chambers 55 which is fluidly connected to a pressurized hydraulic fluid source 87 via one of the first hydraulic fluid ports 54 and the hydraulic fluid control valve 80. It could also be possible for the locking pin 74 to receive hydraulic fluid via one of the second chambers 57 that is fluidly connected to a pressurized hydraulic fluid source 87 via one of the second hydraulic fluid ports 56 and the hydraulic fluid control valve 80.

Given the previously described camshaft phaser 10 and respective retention inserts 78, 78A and respective rolling elements 94, 94A, the following method of operating a camshaft phaser can be utilized.

The first operation step involves providing a camshaft phaser 10 that includes: (i) a stator 40; (ii) a rotor 20 that has a plurality of vanes 22 that form fluid chambers 38 with the stator 40; and, (iii) a pressureless-locked locking assembly 70 that selectively locks the rotor 20 to the stator 40 or selectively unlocks the rotor 20 from the stator 40.

The second operation step involves actuating the locking assembly 70 to unlock the rotor 20 from the stator 40, defining a first unlocked position.

The third operation step involves rotating the rotor 20 relative to the stator 40, causing the locking assembly 70 to roll against the stator 40.

At least a portion of the locking assembly 70 can be received by the locking pin aperture 23 arranged within the rotor 20. Actuation of the locking assembly 70 to the first unlocked position and rotation of the rotor 20 relative to the stator 40 can be accomplished by hydraulic fluid pressure, as provided by the hydraulic fluid control valve 80. The hydraulic fluid control valve 80 is electronically controlled by the electronic controller 88, to manage the timing and control of hydraulic fluid from the pressurized hydraulic fluid source 87.

A third operation step involves actuating the locking assembly 70 to a second locked position, which prevents rotation of the rotor 20 relative to the stator 40. This actuation of the locking assembly 70 to the second locked position can be accomplished by the force generator 76 or bias spring arranged within the locking assembly 70, between the locking pin 74 and the retention insert 78, 78A. The force generator 76 or bias spring can provide a force F2 that is greater than a hydraulic fluid force F1 acting on the locking assembly 70.

While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms encompassed by the claims. The words used in the specification are words of description rather than limitation, and it is understood that various changes can be made without departing from the spirit and scope of the disclosure. As previously described, the features of various embodiments can be combined to form further embodiments that may not be explicitly described or illustrated. While various embodiments could have been described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes can include, but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. As such, to the extent any embodiments are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics, these embodiments are not outside the scope of the disclosure and can be desirable for particular applications. 

1. A camshaft phaser, comprising: a stator; a rotor having: a plurality of vanes that form fluid chambers with the stator; and a locking assembly having: a retention insert disposed within an aperture, the retention insert movable in a longitudinal direction of the aperture and configured to receive a rolling element; a locking pin disposed at least, partially within the aperture; and a bias spring arranged between, the retention insert and locking pin; and in a first unlocked position of the locking assembly, the retention insert is pushed against the stator via a first force and rolls on the stator via the rolling element; and in a second locked position of the locking assembly, the retention insert is pushed against the stator via a second force different than the first force.
 2. The camshaft phaser of claim 1, wherein the locking assembly is configured to roll against a flat axial surface of the stator.
 3. The camshaft phaser of claim 1, further comprising a cover that is non-rotatably attached to the stator, the locking assembly configured to roll against the cover.
 4. (canceled)
 5. The camshaft phaser of claim 1, wherein the rolling element is a ball or a roller.
 6. The camshaft phaser of claim 1, wherein the locking pin is configured to be hydraulically actuated via a groove extending directly from a locking end of the aperture, the groove arranged on an axial face of the rotor.
 7. (canceled)
 8. (canceled)
 9. The camshaft phaser of claim 1, wherein the locking pin protrudes from a locking end of the aperture to engage the stator.
 10. The camshaft phaser of claim 9, wherein the retention insert includes at least one outlet configured to provide an exit pathway for at least one of hydraulic fluid or air from the aperture.
 11. The camshaft phaser of claim 10, wherein an axial face of the rotor is configured with a vent passage extending directly from an end of the aperture.
 12. The camshaft phaser of claim 11, wherein the vent passage is transverse to a central axis of the aperture and extends radially inwardly from the end of the aperture.
 13. The camshaft phaser of claim 1, wherein the aperture is located within one of the plurality of vanes.
 14. (canceled)
 15. (canceled)
 16. A method for operating a camshaft phaser, comprising: providing the camshaft phaser that includes: a stator; a rotor having a plurality of vanes that form fluid chambers with the stator; and, a locking assembly configured to selectively lock the rotor to the stator or selectively unlock the rotor from the stator, the locking assembly having: a retention insert disposed within an aperture the retention insert movable in a longitudinal direction of the aperture and configured to receive a rolling element; a locking pin disposed at least partially within the aperture; and a bias spring arranged between the retention insert and locking pin; and actuating the locking assembly to unlock the rotor from the stator, defining a first unlocked position in which the retention insert is pushed against the stator via a first force; and rotating the rotor relative to the stator, causing the rolling element to roll against the stator; and, actuating the locking assembly to lock the rotor to the stator to prevent rotation of the rotor relative to the stator, defining a second locked position in which the retention insert is pushed via against the stator via a second force different than the first force.
 17. The method of claim 16, wherein the rotor further comprises: a first axial face of the rotor defining a first groove; and, a second axial face of the rotor defining a second groove; and, the first groove extending from a first end of the aperture, and the second groove extending from a second end of the aperture, the first groove configured to deliver pressurized hydraulic fluid to a locking pin, and the second groove configured as a vent passage for the aperture.
 18. The method of claim 16, wherein the actuating the locking assembly to unlock the rotor from the stator step and the rotating the rotor step are accomplished by hydraulic fluid pressure acting on the locking assembly and rotor, respectively.
 19. (canceled)
 20. The method of claim 16, wherein the actuating the locking assembly to lock the rotor to the stator step is accomplished by the bias spring arranged within the locking assembly, the bias spring providing a force that is greater than a hydraulic fluid force acting on the locking assembly in the second locked position.
 21. A camshaft phaser, comprising: a stator; a rotor having: a plurality of vanes that form fluid chambers with the stator; and a locking assembly having: a retention insert disposed within an aperture and configured to receive a rolling element; and: i) in an initial assembly state of the camshaft phaser, the retention insert is fixed to the aperture; and ii) after the initial assembly state of the camshaft phaser, the retention insert is movable within the aperture; and a locking pin disposed at least partially within the aperture; and a bias spring arranged between the retention insert and locking pin; and after the initial installation state: in a first unlocked position of the locking assembly, the retention insert is pushed against the stator via a first force and rolls on the stator via the rolling element; and in a second locked position of the locking assembly, the retention insert is pushed against the stator via a second force different than the first force.
 22. The camshaft phaser of claim 21, wherein the second force is less than the first force.
 23. The method of claim 16, wherein the second force is less than the first force. 